1. Field of the Invention
This invention relates to a method of preparing composite materials in the form of ultra fine particles which mainly comprise organic polymers and have improved physical properties that cannot be obtained from a single
2. Description of the Related Art
Recently, various methods have been tried to improve the physical properties of organic polymers. One method is to form a composite material from organic polymers having different physical properties. The composite material made from organic polymers having different physical properties has improved physical properties that cannot be expected of polymers of one kind, as well as physical properties of each organic polymer from which the new composite is made.
Chemical methods and physical methods are utilized to form a composite from organic polymers. Chemical methods which can be used include block-copolymerization and graft-copolymerization, both of which change the molecular structure of polymers. Physical methods include a blend method which blends other organic polymers with the organic polymer whose physical properties are intended to change.
However, with these methods it is difficult to uniformly combine or conjugate different organic polymers.
On the other hand, it is reported that by making inorganic substances into ultra fine particles whose diameter is at most submicron order, specific properties appear which cannot be obtained for the substances in bulk form. Therefore, making organic substances into ultra fine particles is also expected to show the same effects as ultra fine particles of inorganic substances. To form fine powders of organic substances, grinding method, freeze-drying method, emulsion polymerization method and others can be used. Gas evaporation methods of forming ultra fine particles of organic substances are also disclosed in H. Toyotama and M. Oda "Powder and Industry", Vol. 20, No. 9, 1988. The gas evaporation method comprises the steps of: heating organic substances in inert gas atmosphere, which are intended for fine particles; and cooling the molecules of the organic substances thus evaporated by impinging them against inert gas molecules near an evaporation source to form fine particles.
However, no reports have been made of the preparation of ultra fine particles of composite materials from organic polymers and other materials.